Improving technique is the cheapest way to improve data accuracy and precision. Here are some things to keep in mind when designing your experiment to increase validity.
Take enough time
When making thermal measurements, time is an important factor as it helps us to describe the rate of heat transfer. When taking a measurement, the time before is just as important as the time during heating for exactly the same reasons. Accurate results depend on a stable initial temperature, which requires the sample and sensor to be in thermal equilibrium. To decrease errors caused by temperature changes, use an equilibration time of 10 to 15 minutes before taking a measurement.
Contact
Good contact with the material to be tested is essential for a good measurement. In solids, use a #55 drill bit to create an accurate pilot hole. In dense solids and granular materials, lightly coat the needle with an even coat of thermal grease. The thermal grease will act as a gap filler, and improve results.
Be consistent
Create a specific procedure for testing, including equilibration times, exact pilot hole depth, how thermal grease is applied, sensor orientation in the material, and environmental conditions. If the sensor is being used indoors, the sample and sensor can be placed inside of a cooler to reduce errors caused by light and changing ambient temperatures. Outside, the sensor can also be insulated but if this is not possible, keep the sample and probe out of direct sunlight to reduce heating from the sun.